Safened pesticidal resin compositions for controlling soil borne pests and process for the preparation thereof

ABSTRACT

The present invention relates to novel dry-blended extrudable pesticidal resin composition, extruded pesticidal resin compositions and pelletized pesticidal resin compositions comprising, as the active ingredient, O,O-diethyl S-[[1,1-dimethylethyl)thio]-methyl]phosphorodithioate, O,O-diethyl S-(ethylthiomethyl)phosphorodithioate or a pesticidal chemical wherein said technical grade of said pesticidal chemical has a dermal and/or oral LD50, as measured on rats or rabbits of less than 50 mg/kg. The novel compositions of the present invention are characterized by markedly reduced mammalian toxicity and increased pesticide stability and are essentially free of dust. Further, the present invention also relates to a process for preparing the present safened pesticidal resin compositions.

This is a divisional of application(s) Ser. No. 08/239,850 pending,filed on May 9, 1994, which is a divisional of Ser. No. 07/925,326 filedon Aug. 6, 1992, abandoned, which is a continuation of Ser. No.07/447,960 filed on Dec. 7, 1989, abandoned, which is a continuation ofSer. No. 07/114,821 filed on Nov. 5, 1987, abandoned, which is acontinuation-in-part of Ser. No. 06/933,842 filed on Nov. 24, 1986,abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to safened solid pesticidal resincomposition which previously exhibited toxic dermal effects of theactive pesticide. Examples of the type of active ingredient safened inthe present compositions include O,O-diethylS-[[(1,1-dimethylethyl)-thio]methyl]phosphorodithioate, also known asterbufos, and O,O-diethyl-S-(ethylthiomethyl)phosphorodithioate, alsoknown as phorate. U.S. Pat. No. 2,586,655, issued to Hook on Feb. 19,1952, generally discloses these compounds, and U.S. Pat. No. 2,596,076,issued to Hook on May 6, 1952, discloses terbufos, with U.S. Pat. No.2,759,010, issued to Lorenz et al on Aug. 14, 1956 disclosing phorate.

Both terbufos and phorate are effective soil and systemicinsecticide-nematicides and are commercially used throughout the world.Unfortunately, these compounds, although effectiveinsecticide-nematicides, also are toxic to mammals if they should enterthe mammal's circulatory system through ingestion, inhalation or dermalabsorption. This toxicity is more apparent by the LD50 values of thesecompounds. The acute oral LD50 value in rats of phorate is 1.6-3.7 mgtechnical/kg and for terbufos, 1.6 mg technical/kg. The acute dermaltoxicities in rats are 2.5-6.2 mg technical phorate/kg and 7.4 mgtechnical terbufos/kg animal. Likewise, the acute dermal toxicities onrabbits are 3.1-6.4 mg technical phorate/kg animal and 1.0 mg technicalterbufos/kg anima.

It can be seen, therefore, that there is potential hazard forindividuals exposed to handling the pesticides, such as terbufos andphorate, as well as other such pesticides with acute oral and/or acutedermal toxicities less than about 50 mg/kg. Those individuals involvedin the manufacture, packaging, handling, transportation or use of suchpesticides are at high risk of exposure to said toxic chemicals. Thepotential health safety problems associated with these pesticides havespurred attempts to improve the LD50 values of said pesticides and toprovide compositions which exhibit better margins of safety thanoriginally available. U.S. Pat. No. 4,059,700 issued to Lindsay on Nov.22, 1977, relates to a process to improve the safety of terbufos.Montmorillonite clay is used as a carrier for terbufos and phorate. Thiscomposition provides a product with an LD50 dermal toxicity, on rabbits,of about 27-37 mg/kg. Thus, the dermal toxicity is 2 to 3 times lesstoxic than the compositions available prior to the Lindsay invention.U.S. Pat. Nos. 4,485,103 and 4,343,790, issued to Pasarela on Nov. 27,1984 and Aug. 10, 1982, respectively, also improve the margin of safetyof insecticide-nematicide compositions containing terbufos or phorate.Coating an inert sorptive or non-sorptive granular carrier impregnatedor coated with terbufos or phorate with a finely divided sorptivesubstrate and an acrylic polymer provides a safer composition asevidenced by rabbit dermal LD50 values of about 40 and 80 mg/kg.

Even though these inventions improved the dermal toxicities ofpesticides such as terbufos and phorate, an effective resin-type reducedtoxicity pesticidal composition with residual activity and goodbiological activity was still needed. U.S. Pat. No. 4,554,155 issued toAllan et al on Nov. 19, 1985 discloses controlled-release compositionswhich may contain a wide variety of listed pesticides, includingphorate. These controlled-release compositions specifically containkraft lignin and a biodegradable water-insoluble organic polymer thatreleases the pesticide by structural disintegration of the outersurfaces. As such, these compositions are based on erosion of the matrixto control the release of pesticide. Exposure of the surfaces of thosecompositions to the environment results in the loss of the structuralintegrity of the polymer and/or fracture thereof. Therefore, newsurfaces of the biologically active material-polymer are exposed to theenvironment for further release of the component.

Resins also are used in animal collars and tags to control a variety ofectoparasites which infest such animals. For instance, U.S. Pat. No.4,150,109 issued to Dick et al on Apr. 17,. 1979 discloses animalpesticidal collars containing diazinone or diazoxone, a solidmacromolecular substance chosen from solid vinyl and vinylidenesubstances and a plasticizer. About forty organo-phosphates are listedfor possible incorporation into these animal collars, but terbufos andphorate are not among the pesticides listed. This is not, however,altogether surprising since terbufos and phorate are soil and plantsystemic insecticides and are extremely toxic to mammals.

Another animal collar containing a pesticide is disclosed in U.S. Pat.Nos. 4,134,977 and 4,158,051, issued to Greenberg on Jan. 16, 1979 andJun. 12, 1979, respectively. The Greenberg collars are prepared withdimethyl 1,2-dibromo-2,2-dichloroethyl phosphate, commonly referred toas naled, a plasticized polyvinyl chloride, a substantially non-volatilecarbamate and a surface porosity control agent such aschloro-acetaldehyde, chloral, bromoacetaldehyde, bromal or the like.Those compositions provide controlled release of the insecticide as avapor to surround the animal and as a powder that migrates over the coatof the animal.

U.S. Pat. No. 4,198,782 issued to Kydonleus on Apr. 22, 1980, disclosesa method for making polymeric controlled-release pesticides bygranulating a laminated sheeting material comprising a non-porouspolymeric sheet, a polymeric core film containing phorate or otherinsecticide and a second solid non-porous polymeric sheet adhered to theinsecticide-containing polymeric core material. The thus-preparedsandwich is then chopped into granulated particles. Insect control isobtained with the granulated insecticide compositions prepared asdescribed. However, unfortunately when the laminated materials are cutto the sizes necessary for use in the field, extended activity is lostand little or no safening appears to be achieved.

Other resin compositions are disclosed in U.S. Pat. No. 4,041,151 issuedto Milionis et al on Aug. 9, 1977 and U.S. Pat. No. 4,145,409 issued toPaserela on Mar. 20, 1979. The preparation of insecticidal andacaricidal resin compositions formed into flexible collars for attachingto animals to protect said animals against attack and/or infestation byinsects and acarids is disclosed in those two designed to deliver aninsecticidal or acaridicidal agent having relatively low mammaliantoxicity onto the coat and body of an animal. Pesticides with highmammalian toxicity are not listed for incorporation into resins,moreover, it is not suggested that such incorporation may provide aconcentrate or composition with markedly improved safety.

Thus, although the above-described references provide phorate, terbufosand/or other pesticide compositions with reduced dermal toxicity and/orextended residual activity, the disclosed technology seems insufficientto lower the margin of safety or the oral and/or dermal LD50 values lowenough to remove said pesticides from the hazardous pesticide catagory.

To add to the potential problem, PVC (polyvinyl chloride) compositionswhich contain highly toxic pesticidal agents are not particularly simpleto produce and cannot be prepared by simple incorporation of thepesticide into the PVC. Bulk density for directed application is lackingand effective extended insect control, i.e. throughout the growingseason, plus the necessary safety in handling of the finished product isnot present.

SUMMARY OF THE INVENTION

The present invention provides a solution to these problems unansweredsuccessfully by the state of the art by providing novel dry-blendedextrudable pesticidal resin compositions and pelletized pesticidal resincompositions, in concentrate or finished product form, which combineenhanced safety, effective residual activity of the product and improvedchemical stability of the pesticide in the finished products.

It is an object of the present invention, therefore, to providepesticidal compositions and processes for the preparation thereofwherein said composition contains a highly toxic pesticidal agent,selected polyvinyl chloride resin having appropriate physical andchemical characteristics, selected plasticizers, selected resinstabilizers, lubricants and mineral additives. Surprisingly, thesecompositions provide an agronomically useful product which ischaracterized by non-dusting, markedly reduced mammalian toxicity,significantly increased bulk density, extended residual activity andimproved pesticide stability.

It is an additional object of the present invention to providepesticidal compositions, particularly compositions containing the toxicpesticides with low LD50, and to provide such pesticides in a formhaving significantly improved dermal mammalian toxicity, improvedinsecticidal-nematicidal activity and extended residual effectiveness.

A further object of this invention is to provide pesticidal compositionswhich provide a margin of safety otherwise not found inpreviously-available compositions containing said pesticides.

It is also an object of this invention to provide pesticidalcompositions with improved dermal mammalian toxicity and containingmultiple pesticidal agents that impart different types of biologicalactivity to the locus of treatment.

These and other objects of the present invention will become moreapparent by the detailed description of the invention providedhereinbelow.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to safened pesticidal resin compositionsfor controlling soil borne pests and process for the preparationthereof. The novel safened resin compositions of the present inventionare dry blended, extrudable resin compositions, extruded pesticidalresin compositions and pelletized pesticidal resin compositionscomprising pesticide, the technical grade of said pesticide having adermal LD50, measured on rats or rabbits, of less than 50 mg/kg. Theinvention also relates to the unique process for the preparation of thepresent safened pesticidal compositions.

The compositions of the invention are prepared either as concentrates orfinished products. The concentrates are prepared by dry blending about4.0% to 65%, preferably about 4.0% to 50%, by weight, of a pesticidehaving a dermal LD50, measured on rats or rabbits, of less than 50mg/kg; and about 5.0% to 60%, by weight, of a polyvinylic resin havingan average molecular weight of about 41,000 to 130,000 preferably about50,000 to 69,000. Polyvinyl chloride suspension resin is an example ofsuch a resin. Further, other examples of resins of the presentcompositions include polyvinyl acetate or polyvinyl alcohol resin. Inaddition, of a stabilizing agent or mixture of heat-stabilizing agentsfor the resin and about 0.0% to 2.0%, by weight, of a lubricant areincluded. Silicon dioxide or other sorptive agent is optionally added tothe concentrate at levels of about 0.0% to 10.0%, preferably 0.0% to2.0%.

Pesticides useful in the concentrates and finished products of thepresent invention include, but are not limited to, O,O-diethylS-[[(1,1-dimethylethyl)-thio]methyl]phosphorodithioate, (terbufos);O,O-diethyl S-(ethylthiomethyl)phosphorodithioate, (phorate);(±)-O-ethyl S-phenylethylphosphorodithioate, (fonofos); diethyl1,3-dithiolan-2-ylidene phosphoramidate, (phosfolan);2-methyl-2-(methylthio)propionaldehyde O-methylcarbamoyloxine(aldicarb); O,O-diethyl 2-ethylthioethyl phosphorothioate (demeton);O-ethyl S,S-dipropyl phosphorodithioate (ethoprophos); O,O-diethylO-2-pyrazinyl phosphorothioate (thionazin);2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate, (carbo-furan);1-methylethyl-2[[ethoxy[(1-methylethyl)amino]phosphinothioyl]-oxy]benzoate,(isofenphos); O,O-diethyl S-2-ethylthioethyl phosphorodithioate,(disulfoton); O,O-diethyl O-4-(methylsulfinyl)phenylphosphorothioate,(fensulfothion) and the like. Terbufos and phorate are especiallypreferred in the concentrates and finished compositions of thisinvention because both are excellent plasticizing agents, as well assuperior soil and systemic pesticides.

These two compounds are highly effective for controlling soil borneinsects and nematodes which attack the root systems of plants. They alsoare effective for controlling chewing and puncturing insects andarachnids which feed on the foliage or fluids of plants.

Although this invention is especially useful for improving the safety inhandling of very toxic chemicals referred to hereinabove with acute oralor dermal LD50's, as measured on rats or rabbits, of 50 mg/kg or less,the invention also may be used to improve the safety in handling ofother chemicals, also quite toxic, but which do not have an LD50 of 50mg/kg. For example, compounds which have an acute oral or acute dermaltoxicity of about 50 mg/kg to about 300 mg/kg, or even 500 mg/kg, can beprepared in accordance with the process of the present invention, withthe benefits of enhanced safety and ease of handling. Chemicals in thiscategory include chlorpyrifos, bufencarb, fenthion and the like.

Further, the pesticidal compositions of the present invention provideenhanced extended biological activity, thereby making application easierfor the farmer.

Surprisingly, it has also been found that pesticides in the compositionsof this invention, particularly the phosphate pesticides exhibitmarkedly improved chemical stability as compared to the conventionalgranular pesticide compositions.

Advantageously, the compositions of this invention are effective forcontrolling insects, nematodes and arachnids which feed on the rootsystems and foliage of plants when applied at about 0.25 to 10 kg/ha tothe soil in close proximity to the propagating organ of a plant atplanting time, such as in furrow.

Also, it has now been found that, in addition to the above-mentionedbenefits derived from the compositions of the invention, one or moreadditional pesticides can be used to replace a portion of the mineraladditive and for the secondary plasticizing agent of said compositionsthereby providing safened pesticidal resin compositions with multipleand/or mixed biological efficacies.

The compositions of the invention can, thus deliver a multiplicity ofbiologically active agents including: control agents for soil bornepests, plant nutrients, plant systemic insecticidal and miticidalagents, herbicidal agents, plant growth regulating agents and the like.

The concentrate compositions of the present invention provide aneffective and less hazardous manner for transporting highly toxicpesticides, i.e. pesticides with an oral and/or dermal LD50, measured onrats or rabbits, of less than 50 mg/kg. Although the pesticides usefulin the present invention are among the most effective agents forcontrolling insects, arachnids and nematodes in the soil, particularlyterbufos and phorate, they have LD50 as measured on rats or rabbits, ofabout 1.0 to 50.0 mg.tech/kg, thereby making manufacturing, handling,transporting and using these products a potential hazard. Therefore,extreme care to avoid contact or inhalation of the pesticides was alwaysrequired.

The concentrates of the present invention are useful products and canhave a significant impact on the agricultural industry. Theseconcentrates provide an effective means for reducing dusting andinhalation problems and provide about a 5 to 10 fold margin of safetyover the technical grade pesticides from which they are prepared. Thepresent concentrates also provide about 2 to 2.5 fold margin of safetyover the presently-marketed compositions containing said pesticides.Since these concentrates do not contain the mineral additives used inthe preparation of the extruded and/or pelletized finished compositionsof the invention, they have the added advantage of avoiding addedshipping costs, which would be assessed against the increased weight andbulk of the mineral additives in the finished products.

Although the concentrates of this invention are useful and provideimproved safety in handling of the product in comparison to technicalgrade pesticide, a finished composition is desired for distribution tofarm products distributors, farmers and the like. These finishedcompositions are prepared in the form of extruded strips, strands, rods,sheets or as free flowing, uniform particulate compositions in which theparticulate material may be characterized as dust free beads, granules,pellets, prills or the like.

To prepare the finished products from the above-described concentrates,the concentrate is introduced into a high intensity mixer, along withabout 0.0% to 50%, by weight, preferably 0.2% to 25.0%, by weight, of asecondary plasticizing agent and about 20.0% to 80.0%, by weight, andpreferably about 20.0% to 55.0%, by weight, of a mineral additive. Themixture is blended at an elevated temperature, cooled, passed to anextruder where it is heated to a temperature of about 160° C., extrudedand then pelletized.

When dry blending is needed in the process of the present invention, theconcentrate, mineral additives and secondary plasticizing agents areblended using a high intensity mixer-cooler, conducted at temperaturesof about 75° C. to 110° C. When blending is complete, the mixture iscooled to about 70° C. and passed to an extruder or melt pump. This isthen heats the mixture to a temperature of about 150° C. to 180° C.,preferably about 155° C. to 160° C. The extruder forces the moltenpolymer mixture through a die having a series of holes, preferably in acircular pattern. As the polymer emerges from the die holes, it is cutinto pellets by rotating blades and permitted to solidify as the pelletspass through the cutting chamber. The pellets are picked up in thecutting chamber by a stream of water which transports them to a temperedwater system where they are dried and discharged from the drier. Thepellet water is then filtered, pressurized, cooled and recirculated tothe pelletizer by the tempered water system.

Use of this system for the preparation of the compositions of thepresent invention is important since it provides an essentially closedsystem for handling the toxic pesticidal materials. This systemeliminates dusting problems and captures any toxicant technicalpesticide which may adhere to the surface of the pelleted compositions.Thus, potential environmental pollution problems encountered in themanufacture of convention pesticidal formulations by conventionalmethods are avoided.

While the compositions of the present invention can first be prepared asconcentrates and then further processed to yield finished compositions,a preferred method for preparing the finished compositions involves dryblending about 5% to 60%, based on the weight of the finished product,of a polyvinylic resin with about 20% to 80%, preferably 20% to 55%, byweight of a mineral additive, about 0.2% to 1.5%, preferably 0.2% to1.0%, by weight, of a stabilizing agent or mixture of stabilizing agentsfor the resin and about 0.1% to 1.0%, by weight, of a lubricant. Afterdry blending the mixture of resin, mineral additive, stabilizer andlubricant, the blended mixture is introduced into a high intensity mixerwhere it is admixed with about 1% to 30%, by weight, of the pesticide,0.0% to 50%, by weight, preferably 0.2% to 25.0%, by weight, of asecondary plasticizing agent and about 0.2% to 1.5% of a stabilizingagent. The pesticide, secondary plasticizing agent and stabilizingagent, preferably epoxidized soybean oil, are generally in liquid form.

The mixture then is subjected to high intensity mixing, and thetemperature of the mixture is heated to about 75° C. to 110° C. Themixture is then quickly cooled and charged into an extruder where it isheated to about 150° C. to 180° C. and extruded as a ribbon, strip, rod,strand or the like. The extruded ribbon or strand is then introducedinto a pelletizer where it is formed into small spheres, pellets orbeads.

In the preferred process, the pellets are then introduced into a watertransport system in the event that toxicant pesticide adheres to thesurface of the particles. This water transport system thus serves towash the outer surfaces of the particles, trap any toxicant pesticideadhering thereto and prevents escape of toxicant pesticide into theatmosphere. The water is then separated from the pelletized product, andthe pellets are dried and screened or sieved to obtain product of thedesired pellet size.

Among the pesticides employed in the novel compositions of the presentinvention are terbufos, phorate, aldicarb, demeton, ethoprophos,thionazin, fonofos, phosfolan, carbofuran, isofenphos, chlorpyrifos,disulfoton, fensulfothion, bufencarb, fenthion, with terbufos andphorate preferred.

Polymers useful in the compositions of the present invention includepolyvinyl chloride resins, particularly polyvinyl chloride suspensionresin, polyvinyl acetate and polyvinyl alcohol. These polymers having aweight average molecular weight of about 41,000 to 130,000, preferably50,000 to 69,000. The polymers of the invention are available from avariety of polymer manufacturers, such as Gerorgia Gulf Corporation,which offers the following PVC resins:

    ______________________________________                                        Resin #      Molecular Weight                                                 ______________________________________                                        PVC 1055     41,000                                                           PVC 1060     50,000                                                           PVC 1070     66,000                                                           PVC 1073     69,000                                                           PVC 2073     69,000                                                           PVC 1079     75,000                                                           PVC 1082     89,000                                                           PVC 1091     102,000                                                          PVC 1095     110,000                                                          PVC 1010     123,000                                                          PVC 1110     130,000                                                          ______________________________________                                    

Among the secondary plasticizers useful in the preparation of thecompositions of this invention are the organic phthalates, such as butylbenzyl phthalate octyl epoxytallate and diisononyl phthalate, organicphosphates such as tricresyl phosphate, epoxidized soybean oil,epoxidized linseed oil, epoxidized butyl esters of tall oil, organictrimellitates, such as trioctyl mellitate and organic citrates such asacetyl tributylcitrate, or mixtures thereof.

Useful stabilizing agents effective for stabilizing the resin includestearates, such as zinc/calcium stearates, alkaline earth metalstearate, epoxidized soybean oil, secondary octyl tins and phosphitesand organo barium and cadmium complexes, or mixtures thereof.

Typical mineral additives used in the compositions of the presentinvention include barium sulfate, calcium sulfate, calcium carbonate,clays such as kaolin, bentonite, attapulgite and montmorillonite,cellulose products, mica, wallstonite and fertilizers such as dicalciumphosphate, tricalcium phosphate and the like, or mixtures thereof.

These mineral additives, especially the alkaline earth metal sulfatesand carbonates, are essential components of the extruded andextruded-pelletized products of this invention. While not wanting to belimited by theory, it is believed these mineral additives impart thebulk density to the extrudates that permits the directed applicationinto the furrows or beside the planted crops which they are to protect,thereby inhibiting the movement of the extrudates by wind or rain fromthe locus of their application. These mineral additives also arebelieved to be instrumental in providing relatively uniform and extendedrelease of the pesticide from the extrudate and in aiding thedecomposition of the extrudates in the soil when the growing season isfinished.

Lubricants useful in the present invention to improve the extrudabilityof the compositions include calcium, magnesium, aluminium and glycerolmono stearate, stearic acid, paraffin waxes, low molecular weightpolyethylene and the like.

Since it has now been found that several of the above-said pesticidesused in the compositions of the present invention are plasticizingagents as well as pesticidal agents, when preparing polyvinylic resincompositions of the invention containing pesticide-plasticizing agents,the amount of secondary plasticizing agent required for an extrudablecomposition can frequently be limited to as little as 2% to 10% of theweight finished extruded product. It has also been found that a numberof other pesticidal agents including: herbicidal, insecticidal andnematicidal agents, such as2-chloro-N-(2,6-diethyl-phenyl)-N-(methoxymethyl)acetamide (alachlor)and O,O-dimethyl S-methylcarbamoylmethyl phosphorodithioate (dimethoate)can be substituted for the conventional secondary plasticizing agentsdescribed below and employed in the preparation of the extruded andextrudable compositions of the invention. As such, the resultingextrudates can impart to the locus of treatment not only soil insect andnematode control but also weed control, systemic protection of plantsfrom leaf feeding insects, or broad spectrum insect control dependingupon the pesticide substituted for the secondary plasticizing agent.

Flow Diagram I provides a graphical illustration of the hereinabovedescribed process of manufacture. ##STR1##

The apparatus useful in the dry blending aspects of the process of thepresent invention include high torque intensive mixers and low torquecontinuous ribbon blenders, both with heat-cool capabilities. The dryblend is prepared by charging the vinyl resin, dry stabilizer (Ca/ZnStearate) and filler to a mixer heated to 70° C. The blend is premixedfor 5 minutes. The liquid portion is weighed and charged to a milliporepressure vessel heated to about 70° C. (The liquid portion consists ofthe plasticizer, active ingredient and liquid stabilizers). The dryblend is tumbled at a moderate rate with the liquid portion added over afive minute period. The entire mass is then heated to about 100° C.After adding the liquid, the blend should be free flowing. If not, asmall amount of SiO₂ i.e. an amount of up to about 10.0%, generally 1.0%to 2.0%, is added. The entire mix is cooled and poured into a specialsealable drum or pumped into an extruder, where the composition iscompacted and extruded in a spagetti-like (i.e. strand or rod-like)sheet-like or ribbon-like form. This is then pelletized using an underwater pelletizing system. A hot face air cooled system may, of course,be substituted for the under water pelletizer.

The finished products prepared as described above provide a greatadvantage because they have an increased bulk density of 45 to 100pounds per cubic foot, generally 50-80 pounds per cubic foot compared tothe commercially-available terbufos or phorate clay granulars of 31-40pounds per cubic feet. This allows the farmer to carry more product perload than could be carried if the product were formulated as aconventional granule. Transportation of more active ingredient per loadby truck, tractor, or air delivery is therefore facilitated by the novelformulation of the present invention.

The products of this invention also are more stable to attrition. Sinceterbufos and phorate both pose potential severe inhalation hazards, withLD50s of 35 mg/kg body weight, reduction or elimination of productdusting and/or release of toxicant pesticide vapor is a safetyadvantage. Furthermore, the dust particles, even if formed during theprocess of the present invention, are less hazardous because of theirimproved dermal property.

Additionally, the present processing technology utilizes extrusiontechniques of a continuous closed system process using state of the arttechnologies, thereby eliminating many manufacturing safety and handlingproblems.

The present invention is illustrated by the following examples which areillustrative and not limitative thereof.

EXAMPLE 1

Polyvinyl chloride suspension resin for preparation of safened terbufospellets using placebo study technique with Lindgi-Littleford highintensity mixer and standard PVC/plasticizing technique

In these tests the plasticizing agent tricresyl phosphate is substitutedfor terbufos, O,O-diethylS-[[(1,1-dimethylethyl)thio]methyl]phosphorodithioate.

The composition is prepared by dry mixing at a temperature of 110° C.for about 5 minutes 18%, by weight, of Georgia Gulf PVC 1060, having aweight average molecular weight of 50,000, 55%, by weight, of bariumsulfate and 1.0% by weight, of calcium stearate/zinc stearate resinstabilizer. To this mixture is added 9.0%, by weight, of tricresylphosphate, which is the terbufos placebo substitute. Tricresyl phosphateis selected as the terbufos substitute because, like terbufos, it is aplasticizing agent. Also added are 15%, by weight, of the secondaryplasticizing agent, butyl benzyl phthalate, and 2%, by weight, of thestabilizing agent, epoxidized soybean oil. The mixture is stirred forabout five minutes at 100° C. Silicon dioxide (0.5% by weight) is thenadded, and the mixture is stirred for about 1 minute. This yields afreely flowable particulate composition having an average particle sizeof about 10 to 30 mesh.

The above procedure is also used for blending together 18%, by weight,of the Georgia Gulf PVC 1060, 55% by weight of barium sulfate, and 1.0%by weight of calcium/zinc stearate of a temperature of about 110° C. forabout 8 minutes and then slowly admixing therewith 18% by weight oftricresyl phosphate, 6% by weight of butyl benzyl phthalate and 2.0% byweight of epoxidized soybean oil. This procedure provides a free flowingparticulate composition suitable for extrusion.

Other compositions prepared in the same anner and then extruded arereported hereinbelow. Extrusion is conducted at a temperature of about130° C. to 140° C. The extruded product is in the form of smooth, dustfree, uniform strands.

    ______________________________________                                        Ingredient       % By Weight                                                  ______________________________________                                        PVC-MW 50,000    25                                                           Ca/Zn Stearate    1                                                           CaSO.sub.4       49                                                           Tricresyl Phosphate                                                                             3                                                           Butyl Benzyl Phthalate                                                                         20                                                           Epoxidized Soybean Oil                                                                          2                                                                             100%                                                        ______________________________________                                    

Extruded product in the form of long strands is essentially dust free.

    ______________________________________                                        Ingredient       % By Weight                                                  ______________________________________                                        PVC-MW 50,000     14                                                          BaSO.sub.4       58                                                           Ca/Zn Stearate    1                                                           Tricresyl Phosphate                                                                             8                                                           Butyl Benzyl Phthalate                                                                         18                                                           Epoxidized Soybean Oil                                                                          1                                                                             100%                                                        Dry blend for extrusion.                                                      PVC-MW 50,000    25                                                           Ca/Zn Stearate    1                                                           BaSO.sub.4       49                                                           Tricresyl Phosphate                                                                             3                                                           Butyl Benzyl Phthalate                                                                         20                                                           Epoxidized Soybean oil                                                                          2                                                                             100%                                                        ______________________________________                                    

Extrudate is in the form of long uniform strands.

EXAMPLE 2

Safened polyvinyl chloride suspension resin composition containingterbufos and prepared by the procedure of Example I

Polyvinyl chloride, Ca/Zn stearate and CaSO₄ are blended as described inExample I above, but the blended composition is warmed to 70° C.Terbufos, butyl benzyl phthalate and expoxidized soybean oil are thenadded slowly and blended at 70° C. Addition of 0.05% by weight of SiO₂to the blended mixture gives a free flowing composition which is readilyextruded at 140° C. to give the desired product.

    ______________________________________                                        Ingredient       % By Weight                                                  ______________________________________                                        PVC-MW 50,000    25                                                           Ca/Zn Stearate    1                                                           CaSO.sub.4       49                                                           Terbufos         17                                                           Butyl Benzyl Phthalate                                                                          7                                                           Epoxidized Soybean Oil                                                                          1                                                                             100%                                                        ______________________________________                                    

EXAMPLE 3

Safened terbufos polyvinyl chloride suspension resin composition

Following the procedure of Example 1, polyvinyl chloride with a weightaverage molecular weight of about 50,000 is blended with barium sulfateat a temperature of about 110° C. To this mixture is then addeddiisononyl phthalate plasticizing agent and terbufos, O,O-diethylS-[[1,1-dimethylethyl)thio]methyl]phosphorodithioate. After blending,the mixture is cooled and passed to an extruder where the mixture isheated to 135° C. for eight minutes and then extruded. The extrudate,when evaluated for dermal toxicity, has an LD50 dermal toxicity,measured on rabbits, of 160 mg/kg.

The composition described above contains:

    ______________________________________                                        FORMULA A                                                                     Ingredient       % By Weight                                                  ______________________________________                                        PVC-MW 50,000    14                                                           BaSO.sub.4       60                                                           Terbufos         18                                                           Diisononyl Phthalate                                                                            8                                                                             100%                                                        ______________________________________                                    

The above procedure is repeated with the ingredients indicated inFormula B to form the following composition:

    ______________________________________                                        FORMULA B                                                                     Ingredient      % By Weight                                                   ______________________________________                                        PVC-MW 50,000   14                                                            BaSO.sub.4      60                                                            Terbufos        18                                                            Tricresyl Phosphate                                                                            8                                                                             100%                                                         ______________________________________                                    

This composition is blended, mixed, cooled, heated and extruded asdescribed above, and the extrudate is found to have an LD50 dermaltoxicity, measured on rabbits, of 180 mg/kg. As such, the abovecompositions have about a 4 fold improvement in the margin of safetyover the commercially available terbufos granular products, which havean LD50, measured on rabbits, of about 35-40 mg/kg.

EXAMPLE 4

Safened terbufos polyvinyl chloride suspension resin compositions

In these evaluations, polyvinyl chloride suspension resin having aweight average molecular weight of 50,000 is dry blended with bariumsulfate at room temperature (25° C.). To this mixture is added a mixtureof terbufos and butyl benzyl phthalate. Thereafter, the thus-preparedmixtures are oven cured at 135° C., and the rabbit dermal toxicities ofthe compositions determined. The compositions evaluated are as follows:

    ______________________________________                                        Ingredient       % By Weight                                                  ______________________________________                                        PVC-MW 50,000    14                                                           BaSO.sub.4       60                                                           Terbufos         18                                                           Butyl Benzyl Phthalate                                                                          8                                                                             100%                                                        ______________________________________                                    

The rabbit dermal LD50 for this composition is 320 mg/kg.

EXAMPLE 5

Safened polyvinyl chloride resin compositions pelletized to 18 to 48mesh particle size

Following the procedures of Examples 1-3 above but pelletizing theextruded compositions provides non-dusting, resilent 18-48 mesh pelletscontaining 17% to 23% by weight of terbufos and having dermal LD50's onrabbits, of about 130 mg/kg to 500 mg/kg. The pelletized productdensities are about 60 and 90 lbs/ft³.

The compositions evaluated are described below.

    ______________________________________                                                        % W/W                                                         Ingredient     1          2       3                                           ______________________________________                                        PVC-MW 50,000  25         12      25                                          Ca/Zn Stearate  1          0       1                                          BaSO.sub.4     49         59      --                                          CaSO.sub.4     --         --      49                                          Epoxidized Soybean Oil                                                                        1          0       1                                          Butyl Benzyl Phthalate                                                                        7          6       7                                          Terbufos (86.9%)                                                                             17         23      17                                                          100%       100%    100%                                       ______________________________________                                         1) LD50 rabbit dermal 320 mg/kg, product assay 15% terbufos;                  2) LD50 rabbit dermal 299 mg/kg, product assay 19.4% terbufos;                3) LD50 rabbit dermal 130 mg/kg, product assay 15% terbufos.             

Biological evaluation of compositions 1,2 and evaluated against southernarmyworm shows 100% control of these pests for 10 weeks.

Dermal toxicity of compositions of the present invention are determinedby the following procedure using male albina rabbits as the testanimals.

MATERIALS

Five male albino rabbits weighing approximately 2.2 to 3.5 kilograms areselected for each dosage level. The hair is shaved from the entiretrunk. Saran tubing or "Vinylite" film, VU 1900, 12 inches wide, 0.04millimeters thick and of suitable length to fit around the rabbit isused. One felt cloth bandage measuring approximately 9×18 inches is usedand four pieces of 11/2 inches adhesive tape approximately 14 incheslong are used.

Procedure for Solid Materials

The granular composition to be tested is placed in the center of theplastic film and is moistened with water. The rabbit's underside ismoistened with water, and the animal is placed belly down on thematerial. The plastic film is then brought up and around the animal andsecured at each end with strips of adhesive tape. The felt cloth is thenplaced under the belly and brought up and around the animal and securedto the body with the remaining two strips of adhesive tape.

Procedure for Liquid Materials

The animal is placed on the plastic film and wrapped, and the filmsecured with adhesive tape. The test material is then injected under theplastic with an appropriate size needle and syringe. Then, the feltcloth is placed under the belly and brought up around the animal andsecured with the two remaining strips of adhesive tape. This forms a"cuff"

EVALUATION

Twenty-four hours after dosing, the "cuff" is removed, and any remainingmaterial is brushed away. If the material cannot be removed, the animalis fitted with a fiber collar which prevents the animal from licking thetreatment area. The animals are observed for 14 days, postdosing, notingsigns of toxicity, skin irritation and mortality. At the end of the 14days, the animals are sacrificed and weighted.

By the above procedure, the dermal toxicities of the compositionsdescribed in Examples 3-5 above are determined.

EXAMPLE 6

Biological evaluations of extruded, pelletized PVC terbufos compositions

The following studies were undertaken to compare the initial andresidual performance against 3rd instar Diabrotica undecimpunctatahowardi larvae for various types of PVC granular formulations ofterbufos, as compared to the standard 15 formulation.

In all studies, the dosage of the toxicant pesticide is calculated onthe basis of the field practice of banding granules in a 7 inch bandover the row. Residue studies indicate that terbufos remains in the top3 inches of Soil through the corn growing season. The dosage forterbufos 15G Systemic Insecticide-Nematicide is 8 oz of formulation per1000 feet of row. Therefore, the volume of soil in 1000 feet by 7 inchesby 3 inches is calculated and converted to liters. The amount of activepesticide in that volume is determined and then reduced to the amountrequired for 1 liter of soil. Finally, all dosages are converted tokg/ha equivalents.

The soil for the study is subsampled to make moisture determinations.Initially, the determinations are made by oven drying the samples andweighing them. In later studies, an Aquatest II Photovolt (New YorkCity, N.Y.) is used to measure soil moisture. Since 15% moisture isoptimum for larval survival, an attempt is made to maintain that levelduring the bioassays.

The appropriate amounts of formulation are added to 1 liter of soilwhich had been placed into 4 ml polyethylene bags. The bag is then putinto a tumbler and tumbled for 30 minutes to provide a uniform mixtureof soil and toxicant pesticide. The soil is stored in those polyethylenebags for the duration of the experiment and held at 27° C. Differentsoils used in the studies are identified hereinbelow.

The bioassays are set up by placing 25 ml of the treated soil into 30 mlwide-mouth screw top glass jars. About 1 cc of millet seed is added tothe soil as food for the insects. The jar is capped, and the soil andseed are thoroughly mixed on a vortex mixer. After mixing, 10 southerncorn rootworms about 6-8 days old, are placed into the jar. The jar iscapped loosely and held at 27° C. for 7 days. After 7 days, the soil isremoved from the jars and examined for live larvae. Missing larvae arepresumed dead since dead larvae decompose very rapidly.

                  TABLE I.sup.1                                                   ______________________________________                                        Soil: Silt loam from Atlantic, Iowa                                                                    Dose             Mg For-                                  % Granular Prepara- Kg/  Ingre- %    mulation/                           No.  Formulation                                                                              tion     Ha   dients W/W  L Soil                              ______________________________________                                        1    Terbufos 15.0                                                                            Example 3                                                                              0.25 Terbufos                                                                             18   12.50                                               Formula B     PVC    14                                                                     TCP     8                                                                     BaSO.sub.4                                                                           60                                       2    Terbufos 18.8                                                                            Example 5                                                                              0.25 Terbufos                                                                             23   9.95                                                Formula 2     PVC    12                                                                     BBP     6                                                                     BaSO.sub.4                                                                            59*                                     3    Terbufos 15.0                                                                            Example 3                                                                              0.25 Terbufos                                                                             18   12.50                                               Formula A     PVC    14                                                                     DINP    8                                                                     BaSO.sub.4                                                                           60                                       4    Terbufos 15.0                                                                            (Standard)                                                                             0.25             12.50                                               Com-                                                                          mercial                                                                       product                                                       5    CHECK                                                                         Untreated                                                                ______________________________________                                         .sup.1 Soil is silt loam from Atlantic, Iowa to simulate prairie soil         *Fused at 275 deg. F.                                                    

The Atlantic, Iowa soil used in this test simulates prairie soilscommonly found in the cornbelt. Possibly, this soil reduces the timerequired to detect a break in biological activity of the formulations.This soil is not sterilized. The results are provided in Table II.

                                      TABLE II.sup.1                              __________________________________________________________________________    Terbufos PVC Study                                                            Percent mortality to third instar Diabrofica undecinpunctata howardi                        Dose                                                                              Weeks after soil treatment                                  Formulation                                                                           Preparation                                                                         Kg/ha                                                                             1  2  4  7  8  10 12 14*                                                                              15 17 18*                           __________________________________________________________________________    Terbufos 15.0 g                                                                       Ex 3-B                                                                              0.25                                                                              90.0                                                                             100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            95.0                                                                             96.4                                                                             97.5                                                                             100.0                                                                            100.0                         Terbufos 18.8 g                                                                       Ex 5-2                                                                              0.25                                                                              100.0                                                                            100.0                                                                            100.0                                                                            95.0                                                                             92.5                                                                             100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            100.0                         Terbufos 15.0 g                                                                       Ex. 3-A                                                                             0.25                                                                              77.5                                                                             100.0                                                                            97.5                                                                             100.0                                                                            100.0                                                                            100.0                                                                            95.0                                                                             100.0                                                                            100.0                                                                            100.0                                                                            94.1                          Terbufos 15 g                                                                         Standard                                                                            0.25                                                                              100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            92.5                                                                             95.0                                                                             96.4                                                                             87.5                                                                             7.5                                                                              55.9                          Check         --  10.0                                                                             7.5                                                                              7.5                                                                              7.5                                                                              12.5                                                                             12.5                                                                             7.5                                                                              0.0                                                                              12.5                                                                             7.5                                                                              0.0                           __________________________________________________________________________     .sup.1 Soil is silt loam from Atlantic, Iowa                                  *Abbott's formula calculated on these data due to check mortality in          excess of 15%                                                            

All of the formulations, including the standard, release well during thefirst week of the study, except example 3-A which requires 2 weeks tobecome fully effective. The standard 15G formulation performs poorly(under 90% mortality) by the 15th week of the study. All of the extrudedgranular formulations are 94% to 100% effective through 18 weeks. Thus,all of the experimental formulations give residual persistence superiorto that of the standard in this study.

Study 2 is a duplicate of study 1 except for the soil. The objective isto compare the time required for a break in biological activity of theformulations with the use of sterilized versus non-sterilized soils.

In the sterilized soil, example 3-B took 3 weeks to produce 100%mortality. However, it remains highly effective for 20 weeks. Example3-A has a delayed release of 1 week initially and provides 100% controlthrough 14 weeks at which time its activity drops below an acceptablelevel. The standard 15G formulation is effective until the 20th weekafter treatment in this study. Example 5-2 appears to outlast thestandard, but, it must be noted that the depletion of treated soil atlast sampling reduces the number of replications by half. Thus, theconclusion that Example 5-2 is equal or superior to the standard insterilized soil may not be justified in this case.

                                      TABLE III                                   __________________________________________________________________________    Percent mortality to third instar Diabrotica undecinpunctata howardi                            Weeks after soil treatment - potting soil                                 Dose                                                            Formulation                                                                           Preparation                                                                         Kg/ha                                                                             1* 2  3  5  7  9  12 14 15 17 18 19 20                      __________________________________________________________________________    Terbufos 15.0 g                                                                       Ex. 3-B                                                                             0.25                                                                              0.0                                                                              77.5                                                                             100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            97.5                                                                             100.0                                                                            97.5                                                                             100.0                                                                            100.0                                                                            100.0                   Terbufos 18.8 g                                                                       Ex. 5-2                                                                             0.25                                                                              100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            97.5                                                                             92.5                                                                             97.5                                                                             95.0                                                                             62.5                                                                             100.0**                 Terbufos 15.0 g                                                                       Ex. 3-A                                                                             0.25                                                                              57.5                                                                             100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            67.5                                                                             57.5                                                                             70.0                                                                             75.0                                                                             77.5                                                                             32.5                    Terbufos 15 g                                                                         Standard                                                                            0.25                                                                              100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            100.0                                                                            85.0                                                                             90.0                                                                             97.5                                                                             95.0                                                                             97.5                                                                             55.0                    Check    --   --  0.0                                                                              12.5                                                                             2.5                                                                              7.5                                                                              5.0                                                                              12.5                                                                             17.5                                                                             15.0                                                                             7.5                                                                              5.0                                                                              2.5                                                                              5.0                                                                              15.0                    __________________________________________________________________________     *Abbott's formula calculated on these data due to check mortality in          excess of 15% except when all values = 100%.                                  **Last sample consists of two replicates due to shortage of treated soil.

EXAMPLE 7

Preparation of extruded, pelletized PVC soil insecticide compositions

In these tests the compositions are prepared by admixing about 15 to 17part by weight of a toxic soil insecticidal agent with about 1 part ofepoxidized soil bean oil and 11 to 16 parts of butyl benzyl phthalate.The mixture is heated to a temperature between 45° and 50° C. andstirred continuously. This yields true solutions of the activeingredients in the mixtures. A uniform blend of calcium/zinc stearatestabilizer 0.9-1.0 parts, PVC 2073 molecular weight average molecularweight 69,000 22.47 to 23 parts and anhydrous calcium sulfate 44 to 49parts, is blended and added to the previously prepared solution ofpesticide, epoxidized soybean oil and butyl benzyl phthalate, and mixedto a uniform paste. The mixture is heated to 65° to 75° C. and stirreduntil a uniform free-flowing dry powder is produced.

In these preparations carbofuran and aldicarb do not dissolvecompletely. Therefore sufficient methylene chloride is added to producethe true solution. Thereafter the blend of calcium/zinc stearate, PVCand calcium sulfate is added to the pesticide solution and the mixturestirred. These mixtures with methylene chloride are heated to evaporatesaid methylene chloride. The resulting mixture is heated to 65° to 75°C. and stirred until a dry free-flowing powder is formed.

The thus prepared compositions are then introduced into a melt indexapparatus which is preheated to 155° to 160° C. Ten gram increments areextruded in the form of a strand 2 mm in diameter. The strands areextruded into water in a beaker, then removed and dried. The extrudedstrands are then cut in one inch sequrents and then ground in a krupscoffee mill and screened to obtain the 20/50 mesh particles. Thecompositions thus prepared are reported in table IV below. Particle sizedistribution of the screened particles are reported in Table V. Theextruded compositions thus prepared have been submitted for acute oraland/or acute dermal toxicity determinations.

                  TABLE IV                                                        ______________________________________                                        Extruded Compositions                                                                     Concentration as % W/W                                            Ingredients   A      B      C    D     E    F                                 ______________________________________                                        1.  *a) Carbofuran                                                                              15.0                                                             b) Aldicarb         15.0                                                      c) Chlorpyrifos          15.0                                                 d) Fenvalerate                15.0                                            e) Ethoprophos                      16.67                                     f) Fonofos                               16.67                           2.  Epoxidized Soy Oil                                                                          1.0    1.0  1.0  1.0   1.0  1.0                             3.  Butyl Benzyl  16.0   16.0 11.0 11.0  11.0 11.0                                Phthalate                                                                 4.  Calcium, Zinc 0.9    0.9  1.0  1.0   0.98 0.98                                Stabilizer                                                                5.  PVC 2073      23.0   23.0 23.0 23.0  22.48                                                                              22.47                           6.  CaSO.sub.4, Anhyd.                                                                          44.1   44.1 49.0 49.0  47.87                                                                              47.88                           ______________________________________                                         *IUPAC chemical names are:                                                    1. a): 2,3dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate.                1. b): 2methyl-2-(methylthio)propionaldehyde Omethylcarbamoyloxime.           1. c): O,Odiethyl O3,5,6-trichloro-2-pyridyl phosphorothioate.                1. d): (RS)a-cyano-3-phenoxybenzyl                                            (RS)2-(4-chlorophenyl)-3-methylbutyrate.                                      1. e): Oethyl S,Sdipropyl phosphorodithioate.                                 1. f): Oethyl Sphenyl(RS)-ethylphosphonodithioate.                       

                  TABLE V                                                         ______________________________________                                        Screen Analyses                                                                       24/48                                                                 U.S. Sieve                                                                            Creek-O-Nite                                                                             Percent Retained On                                        Number  Check      A      B    C    D    E    F                               ______________________________________                                        16      0.0        0.08   0.09 0.18 0.09 0.0  0.0                             20      1.0        9.59   9.08 5.77 17.45                                                                              2.97 0.99                            30      41.0       53.83  51.02                                                                              50.79                                                                              52.91                                                                              66.60                                                                              70.50                           40      38.5       24.50  26.63                                                                              27.26                                                                              20.36                                                                              22.08                                                                              21.23                           PAN     19.5       12.00  13.18                                                                              16.00                                                                              9.19 8.35 7.28                            ______________________________________                                    

                  TABLE VI                                                        ______________________________________                                        Toxicity Testing on 15% Pelleted Compositions                                        Technical     PVC Pelleted Compositions                                         Rat Oral Rabbit Dermal                                                                            Rat Oral                                                                             Rabbit Dermal                                      LD50     LD50       LD50   LD50                                      Ingredient                                                                             (mg/kg)  (mg/kg)    (mg/kg)                                                                              (mg/kg)                                   ______________________________________                                        Carbofuran                                                                              11      10,200     100    --                                        Aldicarb 0.9        5        <12.5  >120                                      Chlorpyrifos                                                                           96-270   2000       >500   --                                        Fenvalerate                                                                            3200     2500       --     --                                        Ethoprophos                                                                             62      2.4               200                                       Fonofos    3       25        >100   >400                                      (Dyphonate)                                                                   ______________________________________                                    

EXAMPLE 8

Combinations of Terbufos and Alachlor and/or Atrazine in PVCcompositions

Safened pesticidal resin compositions for simultaneously controllingsoil borne pests and undesirable weed species are prepared by theprocedure of Example 7, excepting that the secondary pesticides, i.e.alachlor and/or atrazine are dissolved or dispersed in terbufos beforethe terbufos is added to the mixture.

The compositions are prepared and extruded in accordance with theprocedures of Example 7 and have the concentrations reported in TableVII below.

                  TABLE VII                                                       ______________________________________                                                    Concentration as % w/w                                            Ingredient    A       B       C    D     E                                    ______________________________________                                        Terbufos technical                                                                          11.50   11.50    5.75                                                                              --    --                                   (87% Real)                                                                    Alachlor (99% Real)                                                                         20.20   --      10.10                                                                              20.20 --                                   Atrazine, technical                                                                         --      21.00   10.53                                                                              --    21.00                                (95% Real)                                                                    Epoxidized Soybean Oil                                                                       1.00    1.00    1.00                                                                               1.00  1.00                                Butyl Benzyl Phthalate                                                                       3.00   19.50   10.00                                                                              14.00 32.00                                PVC 2073      23.00   23.00   23.00                                                                              23.00 23.00                                Ca/Zn Stearate                                                                               1.00    1.00    1.00                                                                               1.00  1.00                                Anhydrous Calcium                                                                           40.30   23.00   38.62                                                                              40.80 22.00                                Sulfate                                                                       ______________________________________                                    

Alachlor is 2-chloro-2',6'-diethyl-N-(methoxymethyl)-acetanilide (IUPACnomenclature. Atrazine is2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine (IUPACnomenclature).

Compositions D and E are used as controls to determine whether alachlorand/or atrazine are herbicidally effective when utilized in alone and/orin the presence of terbufos in the PVC compositions of the invention.

It has now been observed that alachlor is quite soluble in terbufos andcan be substituted for at least a portion of the secondary plasticizerin the compositions.

Atrazine is less soluble than alachlor in terbufos. This is evidenced bycomposition E where 32% of butyl benzyl phthalate is required to providea satisfactory extrudate. Composition B containing 11.5% w/w of terbufosand 21% w/w of atrazine required only 19.5% w/w of the secondaryplasticizer butyl benzyl phthalate. The extrudate B (viewed in crosssection by microscope) reveals a shiny plasticized or fused surface, butthe interior is less well fused.

Herbicidal evaluations of compositions A-E all show herbicidal controlof undesirable plant species. Compositions A-C with terbufos plusalachlor and/or atrazine also provide soil insect control.

EXAMPLE 9

Preparation and evaluation of terbufos 15% granular compositions (SeeExample 12), 15% PVC granular resin composition and 20% PVC granularresin compositions

Following the procedures of examples 1-3 above and then pelletizing theresulting compositions by the process illustrated in Flow Diagram I,yields extruded 15% and 20% terbufos PVC granular compositions and a 20%phorate PVC granular composition. These compositions have theconcentrations reported in Table VIII below.

                  TABLE VIII                                                      ______________________________________                                                     Concentration % w/w                                              Ingredient     A          B       C                                           ______________________________________                                        Terbufos (87% Real)                                                                          17.2       23.0    --                                          Phorate (89.9% Real)                                                                         --         --      23.0                                        PVC 2073       17.2       23.0    23.0                                        Butyl Benzyl Phthalate                                                                       3.5        3.5     3.0                                         Mixed Mono Glycerol                                                                          0.5        0.5     --                                          Stearates                                                                     CaSO.sub.4 Anhydrous                                                                         59.6       48.0    --                                          BaSO.sub.4     --         --      49.0                                        Ca/Zn Stearate 1.0        1.0     1.0                                         Epoxidized Soy Oil                                                                           1.0        1.0     1.0                                                        100.0      100.0   100.0                                       ______________________________________                                    

For evaluation of the above-described terbufos and phorate PVC resincompositions field studies are conducted using the commerciallyavailable terbufos and phorate compositions as standards.

A series of field trials are conducted at farms and universities toevaluate the above-said compositions for controlling corn rootworms andevaluating the compositions for phytotoxicity on grain sorghum.

In the phytotoxicity evaluations grain sorghum is planted in rows 0.9meters apart and 15 meters in length. Four rows per plot are used andeach treatment is replicated 3 times. The test compositions areintroduced into the furrow at the time of planting at the rate of 1.12to 2.24 kg/ha. At intervals of from 14 to 72 days after planting theplots are examined and the number of plants emerged and/or growing ineach plot are counted. At 72 days after planting the percent bloomshowing on plants in treated plots is determined. Data obtained arereported in Table IX below.

                                      TABLE IX                                    __________________________________________________________________________    Grain Sorghum Phytotoxicity Field Trails                                                        University A                                                                          University B                                                                        University C                                           Rate     14 DAT                                                                            38 DAT                                                                            16 DAT                                                                              21 DAT                                                                            72 DAT                                    Treatment                                                                              Kg/ha                                                                             Placement                                                                          #Pl/ha                                                                            #Pl/ha                                                                            #Pl/ha                                                                              #Pl/ha                                                                            % Bloom                                   __________________________________________________________________________    Terbufos 15 G                                                                          2.24                                                                              Inf  --  --  --     9023                                                                             71.7                                      Terbufos 15 PVCG                                                                       2.24                                                                              Inf  --  --  --    12120                                                                             90.9                                      Terbufos 15 G                                                                          1.12                                                                              Inf  23303                                                                             22650                                                                             12466 --  --                                        Terbufos 20 PVCG                                                                       1.12                                                                              Inf  26927                                                                             20532                                                                             19066 --  --                                        Terbufos 15 G                                                                          2.24                                                                              Inf  20207                                                                             17925                                                                             14960 --  --                                        Terbufos 20 PVCG                                                                       2.24                                                                              Inf  27051                                                                             20206                                                                             16133 --  --                                        Untreated Control                                                                      --  --   28517                                                                             26073                                                                             32852 12254                                                                             81.7                                      __________________________________________________________________________     #PL/ha = number of plants per hectare                                    

EXAMPLE 10

Evaluation terbufos PVC granular compositions for corn rootworm control

The standard terbufos 15G 24/48 mesh product contains more particles perpound 4.7×10⁶ than the 20% PVC granular composition of the inventioni.e. 0.92×10⁶. On this basis, the terbufos 15G product would be expectedto have better distribution on application and, therefore, a greaterprobability of better biological efficacy than the 20% PVC granularproduct. Surprisingly, however, the 20% terbufos PVC granular productout performs the standard terbufos 15G product in field trials. Inaddition, the phorate 20% PVC granular product provides better cornrootworm control than the standard phorate 20% granular product.

The root rating system used to evaluate test compositions are asfollows:

    ______________________________________                                        Root Rating System                                                            ______________________________________                                        1.         No feeding                                                         2.         Visible Feeding Scars                                              3.         At least 3 roots chewed to within 1/2                                         inch of the plant                                                  4.         One entire node of roots destroyed                                 5.         Two nodes destroyed                                                6.         Three or more nodes destroyed.                                     ______________________________________                                    

Corn rootworm control is determined in these tests. Row treatments withterbufos 15G standard granules, phorate 20G standard granules or phorate25% PVC granules, are applied through a seven-inch bander mounted on theplanter ahead of the press wheel. Furrow treatments are applied byremoving the bander and allowing the granules to flow from the deliverytube directly into the seed furrow.

Two rows, 15 meters in length; are used for each treatment, and eachtreatment is replicated 2 to 4 times. The results of the tests areaveraged and reported below.

    ______________________________________                                        TREATMENT        N     ROOT RATING                                            ______________________________________                                        Field Studies For Corn Rootworm Efficacy                                      Terbufos 15 G    21    2.12                                                   Terbufos 20 PVCG 21    2.02                                                   HEAVY CORN ROOTWORM PRESSURE; CHECK > 4.5                                     Terbufos 15 G    8     2.28                                                   Terbufos 20 PVCG 8     2.07                                                   ______________________________________                                         *BANDED 1.12 kg/ha                                                            N = number of tests                                                           15 G = 15% granular (standard product)                                        20 PVCG = 20% Polyvinyl chloride granular                                     PR is probability                                                        

    CORN ROOTWORM FIELD EFFICACY DATA                                             TREATMENT         BND    INF                                                  ______________________________________                                        Phorate 20 G      2.64   --                                                   Phorate 25 PVCG   2.58   2.31(5)                                              CHECK             4.54                                                        ______________________________________                                         *7 LOCATIONS SIDE BY SIDE COMPARISONS                                         1.12 Kg/ha banded or infurrow                                                 20 G = 20% granular (standard product)                                        25 PVCG = 25% polyvinyl chloride granular product                             BND = banded                                                                  Inf = infurrow                                                           

In these tests, the lower the root rating the more effective theprotection afforded the root system by the treatment applied.

EXAMPLE 11

Evaluation of test compositions for systemic activity of terbufos,aldicarb and carbofuran PVC granular resin compositions

In these tests the conventional 15% granular compositions of terbufos,aldicarb and carbofuran are used as controls along with an untreatedcheck. The 15% PVC granular compositions of the invention, containingthe above-identified soil insecticides, are prepared by the proceduresof example 7 and the compositions evaluated are as follows:

    ______________________________________                                                     Extruded Compositions                                            Ingredients    A          B       C                                           ______________________________________                                        Carbofuran     15.0       --                                                  Aldicarb       --         15.0                                                Terbufos (87% Real)                                                                          --         --      17.2                                        Epoxidized Soy Oil                                                                            1.0        1.0     1.0                                        Butyl Benzyl Phthalate                                                                       16.0       16.0     3.5                                        Ca/Zn Stearate  0.9        0.9     1.0                                        PVC 2073       23.0       23.0    17.2                                        CaSO.sub.4, Anhydrous                                                                        44.1       44.1    59.6                                        Mono Glycerol Stearate                                                                       --         --       0.5                                                       100.0      100.0   100.0                                       ______________________________________                                    

The evaluation is conducted as follows:

Silt loam prairie soil is placed in pots 8 inches wide by 4 inches deep.The depth of the soil is approximately 3 inches. A furrow 6 inches longand 1 inch deep is made in the center of each pot. Four seeds of radish,Raphanus sativus L., var. Cherry Bell, are placed in each furrow at 2inch intervals. The granular treatments are manually distributeddirectly over the seeds in the furrow. The furrow is closed. When thefirst two true leaves have attained a diameter of approximately 1 inch(11 days after planting) a radish plant in each of two pots perreplicate are infested with 10 green peach aphids, Myzus persicae andcovered with four inch clear plastic drinking cups with the bottomsremoved and replaced with nylon screen. The mortality counts are made 24hours after infestation.

The percent mortality after 24 hours of exposure to the leaves oftreated radish plants is shown below:

The radish plants originally planted are removed from the treated furrowand new seeds are planted 7 weeks after treatment. This procedure isdesigned to avoid the effects of senescence on uptake of the systemicinsecticide.

Aphid mortality counts are made on radish plants 67 days after theoriginal planting and in furrow treatment with the test compositions.Data obtained are reported in Table X below where it can be seen thatthe PVC granular compositions of the invention in all evaluations,provided better systemic control of aphids on replanted radish plantsthan any of the conventional formulations.

    ______________________________________                                        Composition      Kg/ha   % Mortality                                          ______________________________________                                        Terbufos 15 G    0.57    35.0                                                 Terbufos 15 PVCG 0.57    40.0                                                 Terbufos 15 G    1.13    63.2                                                 Terbufos 15 PVCG 1.13    76.9                                                 Aldicarb 15 G    0.55    43.6                                                 Aldicarb 15 PVCG 0.55    48.7                                                 Aldicarb 15 G    1.09    40.0                                                 Aldicarb 15 PVCG 1.09    75.8                                                 Carbofuran 15 G  1.70    24.3                                                 Carbofuran 15 PVCG                                                                             1.70    43.6                                                 Carbofuran 15 G  3.40    36.6                                                 Carbofuran 15 PVCG                                                                             3.40    44.7                                                 ______________________________________                                    

EXAMPLE 12

Evaluation of chemical stability of the pesticide in conventionalgranular pesticide formulation and in PVC resin compositions of theinvention

In this evaluation stability of terbufos is determined in side by sidestress tests of a 15% PVC granular composition prepared as described forformula A, in Example 9 and a standard 15G product from a commercial runcomprising 18.0% terbufos (86% real), 4.0% propylene glycol deactivatorand 78% 24/48 mesh montmorillonite clay granules.

Samples from each of the terbufos 15G (24/48 mesh). standard product andthe 15G PVC granular (24/48 mesh) product are stored for 3 months at 37°C. and 75% relative humidity. The products are assayed at the start andfinish of the test period. Data obtained are reported below.

    ______________________________________                                                     Terbufos Assay                                                   Formulation    Day 1            Day 90                                        ______________________________________                                        Terbufos                                                                      15 G 24/48 mesh                                                                              15.28  15.47     14.73                                                                              14.34                                    Standard Product                                                                             14.83  15.15     14.46                                                                              14.27                                    Terbufos                                                                      15 PVCG 24/48 mesh                                                                           14.65  14.50     14.47                                                                              14.50                                    Resin Product  14.52  14.47     14.49                                                                              14.37                                    ______________________________________                                    

From these data it can be seen that the standard 15G terbufosformulation assays 95.2% terbufos when stored for 3 months at 37° C. and75% relative humidity; whereas, the PVC granular product of theinvention assays 99.5% terbufos after storage for 3 months at 37° C. and75% relative humidity.

From the above data it can be seen that the standard terbufos productcontaining deactivator looses a significant amount of activity on 90days storage; whereas, the PVCG terbufos product of the invention, whichcontains no deactivator, is essentially stable over the same periods andshows little or no loss of product.

What is claimed is:
 1. A method for protecting plants throughout thegrowing season from attack by insects, nematodes and arachnids whichfeed on the root systems and foliage of said plants, said methodcomprising: applying to the soil in close proximity to the propagatingorgans of said plants at the time of planting, a pesticidally-effectiveamount of a pesticidal composition containing about 1.0% to 65.0%, byweight, of a pesticide, the technical grade of said pesticide having anoral and/or dermal LD50, as measured on rats or rabbits, of less than 50mg/kg; about 5.0% to 60.0%, by weight, of a polyvinylic suspension resinhaving a weight average molecular weight of about 41,000 to 130,000;about 0.2% to 2.0% by weight, of a heat stabilizing agent or mixture ofheat stabilizing agents for the resin; about 0.0% to 1.0%, by weight, ofa lubricant; about 0.0% to 50.0%, by weight, of a secondary plasticizingagent; about 20.0% to 80.0%, by weight, of a mineral additive; and about0.0% to 10.0% of silicon dioxide.
 2. A method according to claim 1,wherein said polyvinylic pesticidal resin composition is applied at arate of about 0.25 to 10.0 kg/ha, in furrow with the propagating organof plants being planted.
 3. A method according to claim 1, wherein saidpolyvinylic pesticidal resin composition is banded or broadcast at thetime of planting on the soil over the propagating organs of plants at arate of about 0.25 to 10.0 kg/ha.
 4. A method according to claim 1,wherein said polyvinylic pesticidal resin is a polyvinyl chloridesuspension resin and said pesticide is terbufos, phorate, fonafos,folan, aldicarb, demeton, ethoprophos, thionazin, carbofuran,isofenphos, desulfoton or fensulfothion.
 5. A method according to claim2, wherein said pesticide is O,O-diethylS-[[(1,1-dimethylethyl)-thio]methyl]phosphorodithioate.
 6. A methodaccording to claim 2, wherein said pesticide is O,O-diethylS-(ethylthiomethyl)phosphorodithioate.
 7. A method for simultaneouslyprotecting plants from soil borne insects, mematodes, and arachnids thatattack the root systems thereof or feed on the foliage of said plants,and controlling undesirable plant species in the vicinity of saidprotected plants, providing said protected plants with plant nutrientsor regulating the growth of said protected plants, said methodcomprising: applying to the soil in close proximity to propagatingorgans of plants at planting time, an effective amount of a pelletizedcomposition containing about 1.0% to 35.0%, by weight a soilinsecticide, the technical grade of said soil insecticide having an oraland/or a dermal LD50, as measured on rats or rabbits, of less that 50mg/kg; about 1.0% to 30.0% by weight of a secondary pesticide or mixtureof secondary pesticides; about 5.0% to 60.0%, by weight, of apolyvinylic suspension resin having a weight average molecular weight ofabout 41,000 to 130,000; about 0.2% to 2.0%, by weight, of a heatstabilizing agent or mixture of heat stabilizing agents for the resin;about 0.0% to 1.0%, by weight, of a lubricant; about 0.0% to 50.0%, byweight, of a secondary plasticizing agent; about 20.0% to 80.0%, byweight of a mineral additive; and about 0.0% to 10.0% of a silicondioxide; wherein said composition is a solid resin pesticidalcomposition and has a reduced mammalian toxicity and pesticidestability.
 8. A method according to claim 7 wherein said soilinsecticide is terbufos, phorate, fonofos, phosfolan, aldicarb, demeton,ethopropbos, thionazin, carbofuran, isofenphos, disulfonton orfensulfothion; and said secondary pesticide is a herbicide or mixture ofherbicides compatible with said soil insecticide at amounts about 1.0%to 30%, by weight, of said pelletized composition.
 9. A method accordingto claim 7 wherein said soil insecticide is terbufos, phorate, fonofos,phosfolan, aldicarb, demeton, ethoprophos, thionazin, carbofuran,isofenphos, disulfonton or fensulfothion, and said secondary pesticideis a systemic insecticide and/or systemic miticide comparable with saidsoil insecticide, at amounts about 1% to 30%, by weight, of saidpelletized compesition.
 10. A method according to claim 7 wherein saidsoil insecticide is terbufos, phorate, fonofos, phosfolan, aldicarb,demeton, ethoprophos, thionazin, carbofuran, isofenphos, disulfonton orfensulfothion, and said secondary pesticide is alachlor, atrazine ormixtures thereof.
 11. A method according to claim 7 wherein said soilinsecticide is terbufos, phorate, fonofos, phosfolan, aldicarb, demeton,ethoprophos, thionazin, carbofuran, isofenphos, disulfonton orfensulfothion, and said secondary pesticide is dimethoate.